Does it really make fruit and vegetable products ‘better’?
2016 Market for High pressure processing
High pressure processing (HPP) is one of the most accepted and mainstream of the various ‘advanced processes’ being explored for improved quality and nutrient content in high-value foods. According to Visiongain (https://www.visiongain.com/Report/1623/Food-High-Pressure-Processing-(HPP)-Technologies-Market-2016-2026) , in 2016 the value of the global HPP market was over $11 billion. Market segments benefitting from this technology include premium fruit juices, vegetable products, ready-to-eat meats and seafood. Drivers for this technology are improved flavor, nutrient content, color, textural modifications and shelf-life extension of ‘fresh-like’ products.
Are HPP products really ‘better’ than others?
Use of high pressure for pasteurization and, in combination with heat, for sterilization, requires much less of the heat that is deleterious to sensitive flavor, nutrient, color and other components, than more traditional preservation methods. While traditional thermal processes rely on heat to rupture microbial membranes, HPP accomplishes this at the pressures employed (typically 400-800MPa) with very little increase in temperature. Another tremendous advantage of HPP and other ‘advanced technologies’ is the uniform application of pressure or electric fields to the product as a whole, regardless of package size, shape or composition, rather than heating or freezing from the ‘outside in’. Finally, in some shellfish products such as oysters, HPP reduces foodborne viruses while simultaneously ‘shucking’ or removing the shell (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3590410/#Sec6title) . A fact sheet for food processors, developed by researchers at the Ohio State University, provides a useful overview: http://u.osu.edu/foodsafetyeng/publications/technology-fact-sheets-for-food-processors/
The Food and Drug Administration also describes microbial inactivation using HPP at the following site: http://www.fda.gov/Food/FoodScienceResearch/SafePracticesforFoodProcesses/ucm101456.htm
In an extensive review, our research group found that HPP allowed for retention of the natural vitamin A, B, C, phenolic, mineral and fiber content in fruits and vegetables at the time of harvest (http://onlinelibrary.wiley.com/doi/10.1002/jsfa.4718/abstract ). Researchers reported, for example, that HPP treatments (up to 850 MPa) of orange juice resulted in less than 10% loss in Vitamin C if temperatures are kept below 50C, however at higher temperatures losses occurred.
How much pressure, and for how long?
Numerous studies have evaluated the effectiveness of a range of pressure levels, as well as times, and in general it appears that the preservation effect is imparted during the pressurization and depressurization cycles, regardless of the time at a constant pressure. This means that, once the target pressure is achieved, holding time may be minimized.
Domestic institutions currently carrying out HPP research
National Science Foundation – Center for Advanced Processing & Packaging http://u.osu.edu/capps/ Consortium between North Carolina State University, the Univ. of California-Davis and the Ohio State University
US Food and Drug Administration/Illinois Institute of Technology/Industry – Center for Process Innovation https://www.ifsh.iit.edu/projects/food-processing-and-packaging-current-topics-investigation
US Dept. Of Agriculture – Food Safety and Intervention Technologies Research, Wyndmoor, PA https://www.ars.usda.gov/northeast-area/wyndmoor-pa/eastern-regional-research-center/food-safety-and-intervention-technologies-research/
Also, numerous individual researchers at domestic and international universities
In our next article on HPP, we’ll explore the effects of the raw material, e.g. the variety/type of fruit or vegetable processed, and its maturity, on the end product quality.